In honor of the Eurovision Song Contest, let’s get to know some of nature’s singers. How do birds learn to sing? How does a whale sing? And can a fish serenade his love?
The soloist lark
Birds are nature’s ultimate singers. During springtime, they can be heard across the country, especially at dawn and dusk, but also in between. All birds emit audible sounds, but not all of them actually sing, that is, produce lengthy melodic sequences of whistles and chirps. Most of the singing birds belong are passerines, the largest bird group, consisting of some 6,000 different species.
In most species, the singers are the males, who thus inform the world of their presence, as though telling the females, “Here I am, I've got a beautiful strong voice, choose me!” And the other males, “This spot is taken.” Each species has its own unique song, which can vary from very simple to extremely intricate and sophisticated. The male Chiffchaff (Phylloscopus collybita) has a simple song that, as its name suggests, sounds like “chiff-chaff,” while male larks (Alaudidae) delivers much more complex tunes. The superb lyrebird (Menura) takes things to the extreme, by composing its song from dozens of sounds it picks up in its environment. It mimics not only the song of countless other bird species, but also other sounds, like a camera shutter whirring, an car alarm ringing, and others.
The lyrebird mimicking sounds:
A fledgling readying to sing
The majority of songbirds, however, are content with the one specific song that characterizes their species. How do the males know what to sing? Is the song already embedded in their brains when they're born, just waiting to be sung, or do they have to learn it from other males? The answer is, both. Young males indeed learn from adult males in their environment. Experiments have shown that if young males are raised in isolation, without a chance to hear their species’ song, they will develop a different song, typically simpler and much more elementary, which is dubbed the “acoustic isolation” song.
But fledglings don’t emerge from their eggs with a clean-slate brain, ready to receive whatever is presented. The “acoustic isolation” song will be a simplified version of the species’ song, based on a patterns characteristic of the species. Numerous studies have shown that the fledglings’ learning process includes the ability to identify their species’ song from a very early age: Their heart rate changes and they make more demands for food when they hear their species’ song, in comparison to when they hear the songs of other species. Fledglings can learn the song of another species, if that’s the only song they are exposed to. But if exposed to several songs, including that of their own species, that is the one they’ll learn. This indicates that from the moment they hatch, fledglings’ brains are attuned to learning a specific song.
To some extent, the way fledglings learn to sing is similar to the way babies learn to talk. Like babies, the fledglings initially listen to the sounds made by their elders. They then attempt to repeat them. Initially these efforts aren't too successful, sounding a bit like the disconnected syllables babies make before learning to string them together into words. Over time, the young birds improve their song, until it is no less complex than that of other adults. Because they learn from each other, just as humans do, birds also develop local dialects: Different populations of one species inhabiting distant locations may develop distinct songs over time.
Ted-Ed talk: How birds learn to sing:
The similarity between humans and birds doesn’t stop there. When talking to babies, adults tend to speak more slowly, at a higher pitch, and draw out the syllables. This kind of baby talk is known in professional literature as “Motherese” or “Parentese.” Studies show that babies pay closer attention to motherese than to regular speech, and seem to understand that when adults use it, they are talking to specifically to them. A 2016 research study demonstrated a similar phenomenon in zebra finches (Taeniopygia guttata), whose birdsong has been studied for decades.
The researchers found that male zebra finches changed their song when singing to the fledglings: They extend the pauses between the song’s “phrases,” thereby lengthening the song, and repeat certain elements over and over. They also sing more clearly, “cleaning up their syllables,” as Jon Sakata, who led the study, describes in a Washington Post article. The researchers assume that, as with humans, this “baby talk” helps chicks learn. “We liken that a little bit to how people slow their speech down when talking to infants,” Sakata said. “It’s kind of cute that other animals do something similar.”
Another study published this year on the same birds showed that in addition to the males, who teach the chicks to sing, mothers too have a role. They don’t sing, but provide the practicing fledglings feedback. Researchers showed the chicks a video of a female zebra finch moving about and raising her feathers, movements that the females make when the male song appeals to her and when their offspring sing.
Chicks shown this clip right after singing developed a song that was far closer to that of the mature birds in comparison to chicks who saw the clip without it being linked to when they themselves actually sang. This occurred despite the fact that the females’ “feedback” wasn’t linked to song quality: Researchers showed the clip each time the chicks finished their songs, whether they did well or not. The researchers think that the mother’s reaction encourages her male progeny to continue practicing, which in turn contributes to improving their singing abilities.
Halt! What’s the password?
But what happens if the chick grows up with “adoptive parents” of another species and therefore hears a different song? How can the chick know which song is the “correct” one to use if it wants to lure a female? That’s the situation for the Brown Headed Cowbird (Molothrus ater) which, like the European cuckoo or Israel’s own Shrieking Cuckoo, lays its eggs in other birds’ nests. Mark Hauber, who studies cowbirds, suggested that there’s a kind of “password,” a certain behavior or sound typical to these birds, which impacts the fledglings’ learning. When chicks encounter a mature female cowbird, she activates a password that causes a reaction in their brains. Up to that point, as many times as they see their adoptive parents and hear their song, they will not learn to identify themselves as members of the species, and will not mimic their song. The chicks’ learning mechanism is activated only when there is a cowbird in the environment.
Hauber thinks he’s pinpointed that password: The calls of the mature cowbird, made by both males and females throughout the mating season. Hauber and his colleagues showed that when a hatchling has grown enough to be a chick and registers this call for the first time, changes occur in the chick’s brain: A specific protein is produced in large quantities in the area of the brain responsible for auditory development, and disappears a few hours later. It appears that this change causes the chicks to begin learning from the bird which uttered the “password.”
Unlike other birds, cowbird chicks do not hear their own species’ song as soon as they hatch, but only when they actually leave the nest and are exposed to birds not from their adoptive brood. For this reason, male cowbirds learn how to sing relatively late: They start practicing only in their second year of life, and it takes them another year until they succeed in singing adequately.
What happens if a male cowbird doesn’t meet a bird of the same species during his first years of life? In this case, he will eventually learn to mimic its adoptive parents’ songs. Researchers found that the protein which reacts to the “password” is also produced in a large quantity when the young male begins to learn the “wrong” song. The same learning mechanism is activated, no matter which song is being learned. A male that learns the song of a different species has a serious problem when the time comes to find a mate. Females of his species won't understand what he’s trying to convey and will prefer males with the appropriate song.
Chicks that grow up in foreign nests take much longer to learn the song. The male brown headed cowbird (to the right) courting a female | Wikipedia, Jmalik
The Song of the Ocean
Besides birds, another creature renowned for its singing is the whale. Several types of baleen whales vocalize long sequences of whistles and other sounds, which may last hours and carry through the water for kilometers. The best known and most researched song belongs to the long finned humpback whale (Megaptera novaeangliae).
The way in which whales produce sounds is very different from humans. They transfer air from their lungs to a sac, which may have developed from land mammals’ vocal box – i.e., where our vocal chords are found. But unlike land mammals, the air does not pass through this area on to the extrior. Instead, the flow of air through this vestibular sac creates sound waves, which move through the whale itself and into the water, where they're picked up by other whales. The sac is surrounded by muscles that can change its volume, thereby controlling the flow of air and the sounds it releases.
In humpbacks the males are the singers, and they mainly sing during courtship. It is therefore reasonable to assume that singing fulfills the same role in whales as it does in birds: Attracting females and deterring other males. But humpbacks also sing on other occasions, such as when they're migrating, so their songs may also carry additional meanings
Each humpback pod, as the populations are called, has its own song, which the young are taught by the mature whales. Over time, the song changes: One male begins to sing it slightly differently, adding a new note or removing one, and the other males mimic him. Songs can also transfer from one population to another: Males from eastern Australia, for example, learned the song of males from the western coasts when the two populations encountered each other during migration. Humpback songs leave such a strong impression on people who heard them that they were eventually chosen as one of the “voices of the world,” together with chimpanzee calls, birdsong, the sounds of rain and thunder, human music, and more, and preserved on golden records in the 1977 Voyager spaceship. These records are still on the spaceship which continues to make its way beyond the Solar System, and may bring them to ears very different to our own.
Whales’ song once ruled the oceans with no competition; but in the modern age, human activity has reached into the depth of the seas, disrupting their tranquility. Boats, submarines, oil drills, pipelines, and others fill the ocean with noise, which impacts whales. Researchers from Japan recording humpback songs, discovered that less male humpbacks sang in a radius of half a kilometer from a shipping route. Once a ship passed, males in a radius of 1,200 meters either shortened or stopped their songs altogether, and it took them at least 30 minutes to resume normal behavior. Another study showed that the whales changed their songs in reaction to sonar frequencies. The increasing oceanic noise makes it harder for these animals – and many others – to communicate among themselves, and alters their behavior. Researchers and nature preservationists worldwide have called on governments to reduce noisy marine activities, at least in specific areas and for specific periods during the year, such as mating regions and seasons
Ted-Ed clip on whale songs:
The loneliest whale in the world?
During the Cold War (1947-1991), the American Navy built a system for monitoring ocean sounds called SOSUS (Sound Surveillance System). Its purpose was to track USSR submarines. Able to record every sound it heard, the system’s database primarily included sounds related not to subs or to Russians, but rather, to marine life, including whale songs. In the early 1990s, with the fall of the Soviet Bloc, some of the recordings were released to the public and to scientists. It was then discovered that as early as 1989, microphones in the northern Pacific Ocean had recorded what sounded like the song of the Blue Whale, but not exactly… the frequencies didn’t match. Blue whales sing at 10-40 Hertz, and this song was based on 52 Hertz.
The exceptional whale song:
Over the next few years, additional recordings of this special song were collected. Close examination showed that they almost certainly belonged to one creature which was not part of a pod of whales, which sing at a high frequency. “Perhaps it’s a one of a kind in the Pacific Ocean,” a 2004 article suggested. “Despite precise checks of the sounds heard throughout the year, no other calls with similar characteristics have been identified, and there is only one source each season[SG2] .” Researchers followed “52 Blue,” as the whale was labeled, for 12 years. Each year, they started hearing the song in August and September, and it was repeat over and over in the ocean until January or February, when the annual whale migratory period removed it from microphone recording range.
Much to the scientists’ surprise, the article about the whale with the odd song struck a chord with people worldwide. Mainly, it seems, because the song’s uniqueness “stopped him finding love,” as one newspaper noted. Can other whales hear him? Can he hear them? Was he swimming in complete isolation, singing into the ocean’s waves without any hope of receiving a response?
Thus the scientific name “52 Blue” was abandoned in favor of the more poetic nickname “the loneliest whale in the world,” which came to epitomize all the lonely people out there. Songs, books, and even a play were written about the whale. A young Polish man tattooed the whale’s image on his back after breaking up with his girlfriend. None of this, of course, had any substantial connection to the real whale.
First, there is no reason to assume that other whales cannot hear 52 Blue’s song. Admittedly, it is not in the usual whale song range, but it definitely is in their hearing range. “Blue whales, fin whales and humpback whales: all these whales can hear this guy,” says Cornell University’s Christopher W. Clark in an interview with the BBC. “[T]hey're not deaf. He’s just odd.” Clark note that no small number of unique songs were herd in the past, even if not as at high a frequency as 52 Hertz, but “52 Blue,” he admitted, is “not completely mind-bogglingly unique.”
Obviously, he’s able to eat and live and cruise around. Is he successful reproductively? I haven’t the vaguest idea,” said Mary Ann Daher, one of the authors of the 2004 article. “Is he lonely? I hate to attach human emotions like that. Do whales get lonely? I don’t know. I don’t even want to touch that topic.”
A more scientific question is why would the whale sing so extraordinarily. Many researchers think that 52 Blue is a hybrid, perhaps of a blue whale and a fin whale. Previous research shows that such hybrid whales exist, and their body structure, which differs from both parents’ species, may lead to the emergence of distinctive song frequencies. But that is only a conjecture, since to date, no one has seen 52 Blue, which remains a puzzle to scientists – and a source of comfort to people who feel they haven’t found their place in society.
Birds and whales aren’t the only ones known to burst into song. We usually don’t think of mice, dogs, bats, fish as exceptional singers, but some species of these animals do croon
Let’s start with mice. Alston’s brown mouse (Scotinomys teguina) lives in the highland forests of Central America and communicates through songs. These are squeak sequences that last up to 16 seconds. Each mouse has its own unique song. “This is their bar code that says, ‘This is me,’” says researcher Michael A. Long in an interview with the New York Times. The mice sometime sing when alone, but the songs largely have a social role: Males sing to mark their territory, and both sexes sing during the mating season.
Long brought several mice to his lab and found that they have no small number of requirements. “They’re kind of divas,” he described them. “They need exercise equipment in their cages and specialized diets. But they thrive here.” The mice were housed in adjacent cages, and sang to each other. One student noticed that were doing so in a special way, quite uncommon in animals: They did not sing simultaneously, but rather, took turns doing so, waiting for the other to finish before responding. The conversation continued this way, each mouse beginning to sing a fraction of a second after the other stopped. “They’re polite in conversation,” said Arkarup Banerjee, the postdoctoral researcher in Long’s lab.
Such “taking turns in speaking” is an important characteristic of human conversation, and rare in animals. It requires a high level of auditory and vocal control and the ability to mutually synchronize, to prevent the individuals engaged in conversation from overlapping, and enable them to respond to their dialog partner immediately when the latter falls silent. In an article published some months ago, researchers show that a specific part of the cerebral cortex is involved in these capabilities, and suggest that the same brain regions may also be serving humans when conversing.
Meanwhile, on an island’s mountain tops
In 2016, an expedition of zoologists headed to the mountains in New Guinea’s central region, in search of the island’s highland wild dogs. These canids are relatives of the Australian dingo, resembling it in appearance, but smaller in size. They are known as the singing dogs, and it’s easy to see why: Their unique, high pitched, melodic howls, which they sometimes “sing” together in a choir. Some 300 individuals live in zoos and private homes. In the past, a wild population was known to inhabit the island’s mountain tops, but in the past 50 years, the only evidence of its existence was provided by two blurry photos. The 2016 expedition wanted to track them and find if any singing dogs remained in their natural habitat.
In September of that year, the zoologists discovered a canine footprint in fresh mud in a remote forest. The research team quickly set up cameras on the island’s highest mountain ridges, at an altitude of 4.5 kilometers, which captured more than 140 photos of dogs within just two days. The researchers also saw the dogs themselves and collect feces samples, in order to examine their DNA. Based on the photos, at least 15 individuals – a mix of males, females, and pups – inhabit that region.
The researchers, who had feared that singing dogs had become extinct in nature, but actually found a thriving population, were encouraged by their findings. They are also optimistic about the population’s chances of survival in those remote regions, which place them far from human impact.
Singing dogs (and huskies join in):
Bat love songs
Who would have thought that bats could have one of the most sophisticated and rich vocal repertoires for communications of all animals?” wondered George Pollak of the University of Texas at Austin. But that’s exactly what comes to light in the research he conducted with his colleagues.
Why choose bats for a study on vocal communication? Perhaps just because they were in the area, in multitudes. In Austin, Texas, bats have long become a familiar city landmark. Every evening, more than a million Mexican free-tailed bats (Tadarida brasiliensis) emerge from their “dormitories,” under the Ann W. Richards Congress Avenue Bridge, and fly off to hunt for insects – and amuse the tourists, who come especially to watch them.
The bats also sing, uttering a series of squeaks and whistles, some at higher frequencies than the human ear can hear. Special recording equipment used by the scientists enables them to study the bats’ songs in full. “The sounds are made in a specific, arranged pattern to form a song, and there are actually organized sequences within each phrase,” explained Kirsten Bohn, who led the study. “They are made to attract and lure in nearby females.”
Yes, just like the birds and the whales, bats sing during courtship. The study showed that the sounds they make are not random: Even though each bat has a unique song, some patterns of expression and syllables are repeated, again and again. “We’ve learned the vocal production of bats is very specific and patterned,” Bohn added, “and now we have a model not only to study communication similarities in other animals, but also human speech.”
Sid the bat sings:
Singing like a fish
The summer of 1981 was not a peaceful one in Northern California, at least for the residents of yachts and houseboats. Every night, all night, a strong humming sound vibrated through their floors, shaking and rattling the whole house. Dubbed the “Sausalito Hum” for the town near San Francisco known for its many houseboats, the noise ceased in the fall but returned to disturb the residents in 1984. Some described it as an electrical buzz, others said it sounded like the hum of an engine or a jet, or perhaps a group of oboists playing the same note. No one had a clue as to its source, and theories abounded – getting weirder and weirder: From purification plant pumps to a secret military base, Soviet submarines infiltrating the harbor, all the way to extraterrestrials. The mystery was finally solved in 1985: The Sausalito Hum was actually a fish mating song.
Yes, even fish, desperate to find partners, can raise a racket. In this case, it was the Plainfin midshipman (Porichthys notatus) from the toadfish family, so called because their faces are reminiscent of a toad’s. Many types of toadfish sing during courtship, songs composed of deep groans and “bops.” Their songs are not very enticing to the human ear. “It’s the most God-awful sound,” said John McCosker, director of the San Francisco Aquarium, to the New York Times. “It’s like that scene in every crummy war movie you ever saw where all the B-29's are flying together in formation.” But obviously, it is what female toadfish love.
But solving the mystery didn’t solve the problem for houseboat residents, who continued to suffer from the noise. “It’s like a Chinese water torture,” said Suzanne Dunwell, a city resident. “It may be the mating call of the toadfish, but it plays havoc with the sex lives of people living here.” So, in true Californian spirit, she and her friends decided to turn the event into a festival.
The Humming Toadfish Festival was held several times in the late 1980s. Residents dressed up as fish and played the kazoo, which emanates a sound reminiscent of the toadfish’s love songs. “We figured if we can't beat ‘em, join ‘em,” Phil Frank, crowned “King Toadfish” in 1989, explained to the Los Angeles Times. But not long afterwards, the toadfish found some other place to spend their mating season, and have since returned to Sausalito only occasionally and for brief periods.
The toadfish song:
There’s no all-inclusive consensus for what a “song” is, which would enable us to determine unequivocally which animal sounds are considered songs and which are cries or howls. For example, is the call of jackals a song? What about frog choirs, gathering every night to croak in unison? Perhaps, as in other areas, we’ll just have to go with the idea of “you know a song when you hear it.”
The acoustic range of the animal world encompasses many more creatures, such as crickets and cicadas, but they don’t so much sing as play, producing sound waves not by changing the flow of air exhaled through their lungs (or swim bladder) but by rubbing body parts against each other. Recently, it was even discovered that parrots drum with a stick on trees. The main motivation for singing and playing is, like so many other things in nature, mating; it is typically the males who do the singing, to attract females’ attention. Recent studies are revealing some of nature’s musical secrets, and hint that there are plenty of singers just waiting to be discovered.